For purposes of highway shipment, unit loads of wall board, lumber and the like are routinely placed on a flatbed semi-trailer which in turn is attached to, and supported by a fifth wheel device on a modern truck tractor.
Currently, semi-trailers of the type referred to are primarily constructed of longitudinal and transverse steel support members, attached to and covered by heavy gauge sheet metal flooring or decking sections, resulting in a platform-like upper surface upon which the units loads of freight are loaded.
Normally semi-trailers are loaded by utilizing standard motorized forklift trucks. Forklift trucks are commonly used for moving sawed lumber and other similarly stacked material. In connection with this moving it is necessary that space be provided beneath the stacks of lumber to enable the forks to be placed under the lumber in order that it may be lifted by the forklift truck and carried to a desired location. Similarly, at the new location where it is desired to deposit the lumber it is necessary that space be provided so that the forks may be withdrawn from the stack. This space has usually been provided by means of dunnage boards arranged transversely to the pile of lumber and located between the lowest tier of freight and the flatbed semi-trailer platform-like upper surface, as well as between each subsequent tier of freight which are of sufficient thickness to permit the fork to be inserted under the load. Typically such boards might be 4 inches×4 inches. The dunnage has two faces, a first face which is located adjacent to the bed of the vehicle and a second face, generally called the working face, which is placed adjacent to the load and a second face which is located adjacent to the vehicle surface on which the load is supported.
The dunnage allows for space in which the fork-like projections of a forklift truck can be maneuvered during loading and unloading operations, as well as providing support for the unit freight loads during transport. In most cases, the dunnage is formed from the same type of material as the freight being transported. This will prevent damage to the freight during transport over rough roadways which would otherwise occur if there were direct contact between the freight and harder surfaces such as steel for example.
However, there are many instances when simply placing a 4×4 board beneath the load does not elevate the load far enough above the support deck to permit off-loading equipment to get under the load. Often, steel companies use overhead cranes to off-load product. Overhead cranes requires taller dunnage to make placement of lifting slings easier. If such a situation is anticipated, drivers often simply place another board on top of the 4×4 boards. This is a very unsafe practice.
Still further, in some instances dunnage might move either during use or during storage. Either situation is not desirable.
Therefore, there is a need for a dunnage element that can be as tall as necessary while still being stable in use and/or in storage.
Still further, many loads must be secured using straps or the like. If the dunnage has sharp edges, the straps may be damaged. Therefore, there is a need for a dunnage element that is not likely to damage tie-down straps.
Placement of dunnage is also important, and it would be desirable to provide a dunnage element that is easily grasped and moved.